addShiftPopup.fxml

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.ComboBox?>
<?import javafx.scene.control.DatePicker?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.VBox?>

<VBox maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/17" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.example.schedulerapp.Controller">
   <children>
      <HBox prefHeight="100.0" prefWidth="200.0">
         <children>
            <Label text="Date" />
            <DatePicker fx:id="addShiftDatePicker" />
         </children>
      </HBox>
      <HBox fx:id="addShiftEmployeeHBox" prefHeight="100.0" prefWidth="200.0">
         <children>
            <Label text="Employee" />
            <ComboBox fx:id="addShiftEmployeeBox" onMouseClicked="#populateEmployeeBox" prefWidth="150.0" />
         </children>
      </HBox>
      <HBox prefHeight="100.0" prefWidth="200.0">
         <children>
            <HBox prefHeight="100.0" prefWidth="200.0">
               <children>
                  <Label text="Start Time" />
                  <ComboBox fx:id="addShiftStartTimeBox" onMouseClicked="#addShiftTimeBoxClicked" prefWidth="150.0" />
               </children>
            </HBox>
            <HBox prefHeight="100.0" prefWidth="200.0">
               <children>
                  <Label text="End Time" />
                  <ComboBox fx:id="addShiftEndTimeBox" onMouseClicked="#addShiftTimeBoxClicked" prefWidth="150.0" />
               </children>
            </HBox>
         </children>
      </HBox>
      <Button fx:id="addShiftSubmitButton" mnemonicParsing="false" onMouseClicked="#addShiftSubmitClicked" text="Submit" />
   </children>
</VBox>